Problem: $ { \left[\begin{array}{rr}{4} & {-1} \\ {4} & {-1} \\ {0} & {4}\end{array}\right]+\left[\begin{array}{rr}{-1} & {0} \\ {3} & {1} \\ {2} & {3}\end{array}\right] = {?} } $
Solution: To find the sum of two matrices, add the corresponding items between each matrix. ${\left[\begin{array}{rr}{4}+{-1} & {-1}+{0} \\ {4}+{3} & {-1}+{1} \\ {0}+{2} & {4}+{3}\end{array}\right]}$ Now, simplify: ${\left[\begin{array}{rr}{3} & {-1} \\ {7} & {0} \\ {2} & {7}\end{array}\right]}$